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The Single UNIX &reg; Specification, Version 2<br>
Copyright &copy; 1997 The Open Group

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<h4><a name = "tag_000_010_617">&nbsp;</a>NAME</h4><blockquote>
wcstod - convert a wide-character string to a double-precision number
</blockquote><h4><a name = "tag_000_010_618">&nbsp;</a>SYNOPSIS</h4><blockquote>
<pre><code>

#include &lt;<a href="wchar.h.html">wchar.h</a>&gt;

double wcstod(const wchar_t *<i>nptr</i>, wchar_t **<i>endptr</i>);
</code>
</pre>
</blockquote><h4><a name = "tag_000_010_619">&nbsp;</a>DESCRIPTION</h4><blockquote>
The
<i>wcstod()</i>
function converts the initial portion of the wide-character string pointed to by
<i>nptr</i>
to
<b>double</b>
representation.
First it decomposes the input wide-character string into three parts: an
initial, possibly empty, sequence of white-space wide-character
codes (as specified by
<i><a href="iswspace.html">iswspace()</a></i>);
a subject sequence interpreted as a floating-point
constant; and a final wide-character string of one or more unrecognised
wide-character codes, including the terminating null
wide-character code of the input wide-character string.
Then it attempts to convert the subject sequence to a
floating-point number, and returns the result.
<p>
The expected form of the subject sequence is an optional + or -
sign, then a non-empty sequence of digits optionally containing a
radix, then an optional exponent part.
An exponent part consists of e or E,
followed by an optional sign, followed by one or more decimal digits.
The subject sequence is defined as the longest initial subsequence of
the input wide-character string, starting with the first non-white-space
wide-character code, that is of the expected form.
The subject sequence contains no wide-character codes if the
input wide-character string
is empty or consists entirely of white-space wide-character codes,
or if the first wide-character code that is not white space other
than a sign, a digit or a radix.
<p>
If the subject sequence has the expected form, the sequence of
wide-character codes starting with the first digit or the radix
(whichever occurs first) is interpreted as a floating constant as defined in
the C language, except that the radix is used in
place of a period, and that if neither an exponent part nor a
radix appears, a radix is assumed to
follow the last digit in the wide-character string.
If the subject sequence begins with a minus sign, the value
resulting from the conversion is negated.
A pointer to the final wide-character string is stored in the
object pointed to by
<i>endptr</i>,
provided that
<i>endptr</i>
is not a null pointer.
<p>
The radix is defined in the program's locale (category LC_NUMERIC).
In the POSIX locale, or in a locale where the radix is
not defined, the radix defaults to a period (.).
<p>
In other than the POSIX
locale, other implementation-dependent subject sequence forms may
be accepted.
<p>
If the subject sequence is empty or does not have the expected
form, no conversion is performed; the value of
<i>nptr</i>
is stored in the object pointed to by
<i>endptr,</i>
provided that
<i>endptr</i>
is not a null pointer.
<br>
<p>
The
<i>wcstod()</i>
function will not change the setting of 
<b>errno</b>
if successful.
<p>
Because 0 is returned on error and is also a valid return on success, an
application wishing to check for error situations should set
<i>errno</i>
to 0, then call
<i>wcstod()</i>,
then check
<i>errno</i>.
</blockquote><h4><a name = "tag_000_010_620">&nbsp;</a>RETURN VALUE</h4><blockquote>
The
<i>wcstod()</i>
function returns the converted value, if any.
If no conversion could be performed, 0 is returned
&nbsp;and
<i>errno</i>
may be set to [EINVAL].
<p>
If the correct value is outside the range of representable values,
&plusmn;HUGE_VAL is returned (according to the sign of the value), and
<i>errno</i>
is set to [ERANGE] .
<p>
If the correct value would cause underflow, 0 is returned and
<i>errno</i>
is set to [ERANGE] .
</blockquote><h4><a name = "tag_000_010_621">&nbsp;</a>ERRORS</h4><blockquote>
The
<i>wcstod()</i>
function will fail if:
<dl compact>

<dt>[ERANGE]<dd>
The value to be returned would cause overflow or underflow.

</dl>
<p>
The
<i>wcstod()</i>
function may fail if:
<dl compact>

<dt>[EINVAL]<dd>
No conversion could be performed.

</dl>
</blockquote><h4><a name = "tag_000_010_622">&nbsp;</a>EXAMPLES</h4><blockquote>
None.
</blockquote><h4><a name = "tag_000_010_623">&nbsp;</a>APPLICATION USAGE</h4><blockquote>
None.
</blockquote><h4><a name = "tag_000_010_624">&nbsp;</a>FUTURE DIRECTIONS</h4><blockquote>
None.
</blockquote><h4><a name = "tag_000_010_625">&nbsp;</a>SEE ALSO</h4><blockquote>
<i><a href="iswspace.html">iswspace()</a></i>,
<i><a href="localeconv.html">localeconv()</a></i>,
<i><a href="scanf.html">scanf()</a></i>,
<i><a href="setlocale.html">setlocale()</a></i>,
<i><a href="wcstol.html">wcstol()</a></i>,
<i><a href="wchar.h.html">&lt;wchar.h&gt;</a></i>,
the <b>XBD</b> specification, <a href="../xbd/locale.html"><b>Locale</b>&nbsp;</a>.
</blockquote><h4>DERIVATION</h4><blockquote>
Derived from the MSE working draft.
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UNIX &reg; is a registered Trademark of The Open Group.<br>
Copyright &copy; 1997 The Open Group
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